Field of the Invention
The present invention relates to a driver bit that is detachably attached to a rotating tool such as an electric tool and an air tool and that is used for tightening or loosening a screw by transmitting the rotational torque of the rotating tool.
Background Art
A driver bit that is attached to a rotating tool such as an electric tool and an air tool and that is used for tightening or loosening a screw is known (see JP 2013-049100 A).
As shown in FIG. 15, this driver bit includes a bit body 201, tips 202, and locking grooves 203, and is used by being inserted into a socket provided in a tool coupler (such as an anvil) of the rotating tool such as an electric driver. The socket of the tool coupler is hexagonal (specifically, defined by the inner circumferential surfaces of a hexagon), and locking balls are exposed inwardly (see, for example, the reference numeral 34 in FIG. 2A and FIG. 2B). The locking balls are generally arranged at least either of the vertex positions of the hexagon and the center positions of sides forming the hexagon, and are movable in the radial direction of the socket.
The bit body 201 is a portion to which the rotational torque is transmitted from the rotating tool, and has a hexagonal outer circumference (outer circumferential surfaces) as viewed in the direction of a shaft center c1.
A tip 202 has a cross blade that is fitted to a cross recess formed on a screw head. As shown in FIG. 16, the cross blade is formed by four blade forming grooves 204 that extend outwardly from the shaft center c1 in directions orthogonal to each other, as viewed in the direction of the shaft center c1. Each of the blade forming grooves 204 is arranged so that a center line c2 of the blade forming groove 204 coincides with a line connecting the shaft center c1 and a vertex position on the outer circumference of the bit body 201 or a line connecting the shaft center c1 and a center position of a side on the outer circumference of the bit body, as viewed in the direction of the shaft center c1.
A locking groove 203 extends in the circumferential direction between the tip 202 and the bit body 201, into which the locking balls enter when the tip 202 is inserted into the socket of the tool coupler of the rotating tool. In this way, the locking balls enter into the locking groove 203, thereby allowing the tool coupler of the rotating tool to lock a driver bit 200. Specifically, when the driver bit 200 is about to fall out of the socket, the locking balls abut the sidewall of the locking groove 203 so as to suppress the movement of the driver bit 200. This prevents the driver bit 200 from falling out of the socket.